The present invention broadly relates to transport and storage apparatuses for printed products or the like and, more specifically, pertains to a new and improved construction of an apparatus for the intermediate storage of printed products.
Generally speaking, the apparatus of the present invention is intended for the intermediate storage of printed products, such as newspapers, magazines, periodicals and the like in imbricated product formation and comprises a winding mandrel or arbor for winding up the imbricated product formation and arranged to be rotatable and to be driveable at least during such winding up operation. A conveyor device conveys the imbricated product formation to the winding mandrel or arbor. A winding band or strap is capable of being connected to the winding mandrel or arbor. A tensioning device places the winding strap under a prescribable tension. The winding strap is wound between coil layers of the imbricated product formation during such winding up thereof. The conveyor device supplies a stream of the imbricated product formation conjointly with the winding strap in "underfeed" to the winding mandrel. The imbricated product formation arrives at the winding mandrel with leading edges of the printed products in contact with the winding mandrel or the last wound coil thereof, as the case may be.
In an apparatus known from the German Patent No. 2,207,556, granted June 12, 1975 folded printed sheets arriving in imbricated product formation are conducted between two guide bands or straps unwound from rolls and the stream or flow of sheets enclosed between this guide strap pair is conducted in overfeed to a winding mandrel preferably provided with side flanges or cheek plates and upon which the ends of the guide bands or straps are fastened, so that during the spiral coiling or winding-up operation, disturbances of the winding-up process at high machine speeds can be eliminated by the constant presence of two-sided containment of the sheets between the strap pair.
Although high operating speeds can be achieved with this known apparatus, the compactness prerequisite for a high storage capacity cannot be achieved since the compressible folded printed sheets within the coil or product package, both individually and as part of the imbricated product formation, can be only slightly compacted due to the direction of coiling resulting from winding up in overfeed. The result is a relatively loose coil wound product or product package having a storage capacity which leaves a great deal to be desired with respect to a given diameter of coil. Furthermore, narrow limits are placed upon the coil or package diameter.
These disadvantages do not arise in the apparatus known from the German Patent Publication No. 3,123,888 corresponding to the U.S. Pat. No. 4,438,618 granted Mar. 27, 1984. Since each inner coil layer or winding within the coil or product package formed by "underfeed" delivery of the imbricated product formation and supported on the winding strap or band--also referred to as a separation layer--can turn with respect to its surrounding or next adjacent outer or outer coil layer or winding without any mutual blocking in the direction of winding, it is possible, by prescribing the winding strap tension, to tighten or wind up the winding strap and with it the imbricated product formation supported between the individual coil layers of the winding strap in the manner of a watch spring. This results in a thoroughly compact coil or product package in which the firmly compacted and therefore radially rigidly compressed coil layers or windings of the printed products, such as the newspapers, magazines, periodicals or the like are in intimate contact.
The tension forces which must be exerted on the winding strap during this clock-spring-like winding-up or tightening are unexpectedly low. One of the determining factors is that the "underfeed" delivery of the imbricated product formation leads to a desired compression and compaction thereof. As a result of the continuous increase of the winding radius, the winding speed of the winding strap upon the coil or product package, and therefore the delivery speed or linear infeed velocity of the imbricated product formation, is greater than the peripheral or circumferential speed of the outer coil layer of the product package at that point at which the product spines of the currently arriving newspapers or magazines come into contact with the outer coil layer. As a consequence, the product spine is instantaneously retarded, braked or decelerated and conveyed further at the lower peripheral or circumferential speed corresponding to the momentary winding radius. The deceleration of the product spine, in turn, leads to a deceleration of the entire product copy or product. In the meantime, the subsequent product copy or product is being conveyed without hindrance and is displaced over the rear side of the precursive product copy or product until its product spine contacts the wound coil or package and is gripped in the clamping gap between the latter and the precursive product copy or product and is conveyed further at the lower peripheral or circumferential speed of the wound product coil. These actions are repeated from product copy to product copy, so that the imbricated product formation, as it is fed into the wound package coil by the tensioned "underfeed" winding strap, is compressed and correspondingly compacted. This fulfills the prerequisite for a firm wound package or coil. Since the compressibility of the imbricated product formation is increased by the compaction, so that the weight of the printed products, such as the newspapers or magazines carried by the loops or coils of the winding strap is transmitted to the printed products lying above the winding mandrel axis and at that location induce a compression, so that the thickness of the upper part of the wound package or coil is reduced and the thickness, respectively the radius, of the lower coil portion of the wound package is increased since the compression in the upper region enables a deflection or sagging of the loops or individual coils and a loosening of the coil layer of the wound package. When winding up, this leads to the excessively long next-outer coil layers rolling or sliding upon their respectively adjacent inner coil layers, similar to the rolling of an internally toothed planetary gear ring on a rotating pinion gear. During this rolling action, the winding mandrel or arbor (winding drum) can advance due to the presence of a free-wheeling action and, in a secondary winding up process, gradually tightens the loose coil layers of the wound package upon the compacting core of the product coil or package simultaneously with the winding up of the imbricated product formation from the exterior. Naturally, the weight of the printed products which leads to the compression of the currently uppermost coil layers increases, which is also advantageous for the compacting secondary winding-up operation. This entire procedure is made possible by the free-wheeling action leading to the re-coiling of the inner coils or coil layers of the product package upon the winding mandrel or upon one another during the formation of the product coil or package by the "underfeed" delivery of the imbricated product formation stream by means of a winding strap connected to the driven winding mandrel or arbor, i.e. simultaneously with the formation of the coil layers on the periphery of the wound product coil or package.